Division of Compensation Analysis and 

Support Program Evaluation Report

Document Number: DCAS-PER-036

Effective Date: 4/5/2012

Revision No. 0

Blockson TBD Revision Page 1 of 3

Author: signature on file Date: 4/5/2012 

 Dave Allen, HP Team Leader

Approval: signature on file Date: 4/5/2012 

 J.W. Neton, Associate Director for Science

Supersedes: None

RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

4/5/2012

EFFECTIVE 

DATE

4/5/2012

REV. NO. 

0

DESCRIPTION

New document to determine which 

previously completed claims require 

evaluation for the affect of revising the 

Blockson TBD.

1.0 Description

Revision 3 of the Blockson Chemical Company Technical Basis Document (DCASTKBS-0002) was issued on 12/20/2010. The previous version (revision 2) was issued on 

11/21/2007. PER-020, issued on 7/31/2007, evaluated the effect of all changes that were 

made to the Blockson Chemical Company Technical Basis Document (TBD) prior to that 

date. This resulted in a request to DOL for the return of all previously completed 

Blockson claims that had a probability of causation of less than 50%. Once returned, a 

new dose reconstruction was completed for each using the version of the TBD current at 

that time. Revision 1 of the TBD was current when PER-020 was issued. However, 

revision 2 was issued a short time later on 11/21/2007 prior to any claims being 

completed using revision 1. Therefore, this PER only considered the changes that were 

made between revision 2 and revision 3. This information is summarized below.

Revision 0 all claims completed using revision 0 were requested returned (PER-020).

Revision 1 No claims were completed using this revision

Revision 2 The subject of this PER

Revision 3 The current version of the TBD

2.0 Issue Evaluation

Some changes in revision 3 caused the calculated dose to decrease. Most notably was the 

change in the covered period to eliminate 1961 and the second half of 1960. Also, an 

SEC was designated for Blockson between 3/1/1951 and 6/30/1960 based on the inability 

to estimate radon dose with sufficient accuracy. Therefore, radon dose in that time frame 

was removed from the TBD. 
Division of Compensation Analysis and

Support Program Evaluation Plan Document Number: DCAS-PER-036

Effective Date: 4/5/2012 Revision No. 0 Page 2 of 3

The changes that caused in increase in dose are:

1. An increase in the radon exposure during most of the residual contamination 

period. The years in which the exposure increased are from 1963 to the end of the 

residual contamination period.

2. An increase in particulate intakes during the residual period after 1977. 

3.0 Plan for Resolution or Corrective Action

Two separate populations of claims potentially affected by this revision were evaluated 

based on the two increases in dose. The criteria used to determine the first population is 

associated with the increase in radon exposure. The criteria are:

1. Probability of Causation (PC) less than 50%;

2. Most recent version of the dose reconstruction approved by DCAS on or prior to 

December 20, 2010 (issue date of the current TBD revision).

3. Employed at the Blockson Chemical Company after 1962.

4. Verified cancer of a respiratory tract organ.

These criteria were used to generate the list of 4 potentially affected claims. 

The criteria used to determine the second population is associated with the increase in 

particulate intakes after 1977. The criteria are:

1. Probability of Causation (PC) less than 50%;

2. Most recent version of the dose reconstruction approved by DCAS on or prior to 

December 20, 2010 (issue date of the current TBD revision).

3. Employed at the Blockson Chemical Company after 1977.

These criteria were used to generate the list of 32 potentially affected claims. 

3.2 Determination of claims which will not change due to TBD revision. 

Three of the four claims associated with the first issue meet the criteria for inclusion in 

the SEC designated for Blockson. None of the three had additional cancers for which 

medical benefits could be sought. The compensability of these claims is therefore no 

longer dependent on a dose reconstruction. The dose for the remaining claim was 

recalculated using all current dose reconstruction methods including the current version 

of the TBD. From that recalculated dose, a new probability of causation was determined. 

The new probability of causation increased to 11.11%. The list of four claims will be

forwarded to DOL indicating which determination was made of each.

For the second issue, the particulate intakes were lower from revision 2 to revision 3 

through 1977 and higher after. The larger intakes are associated with the earliest dates. 

Therefore, the total intake for a particular claim could increase or decrease depending on 
Division of Compensation Analysis and

Support Program Evaluation Plan Document Number: DCAS-PER-036

Effective Date: 4/5/2012 Revision No. 0 Page 3 of 3

the time frame actually employed. The residual period previously began on 4/1/1962 but 

was changed to 7/1/1960 due to a change in the covered period. Intakes between these 

dates are now lower due to the end of covered operations. The intake rates were 

integrated for both versions of the TBD from varying starting dates to the end of the 

residual period. Comparing this integration determined that anyone with employment 

starting after 1974 and continuing through the end of the residual period would have a 

higher intake under revision 3. Those with employment starting earlier would have a 

lower intake due to the lower intake rates prior to 1978. It should be noted that those 

with employment ended prior to the end of the residual contamination period would have 

a lower intake than this analysis showed.

All 32 claims with employment after 1977 had a start date prior to 1975. Twenty nine of 

those had employment prior to 4/1/1962. For each year prior to 1962, intake rates in 

revision 3 are lower than revision 2. Therefore, the particulate intake for each of the 32 

claims would decrease with revision 3 and none need further evaluation.